Gene expression profile analysis of primary glioblastomas and non-neoplastic brain tissue: identification of potential target genes by oligonucleotide microarray and real-time quantitative PCR

The prognosis of glioblastomas is still extremely poor and the discovery of novel molecular therapeutic targets can be important to optimize treatment strategies. Gene expression analyses comparing normal and neoplastic tissues have been used to identify genes associated with tumorigenesis and potential therapeutic targets. We have used this approach to identify differentially expressed genes between primary glioblastomas and non-neoplastic brain tissues. We selected 20 overexpressed genes related to cell cycle, cellular movement and growth, proliferation and cell-to-cell signaling and analyzed their expression levels by real time quantitative PCR in cDNA obtained from microdissected fresh tumor tissue from 20 patients with primary glioblastomas and from 10 samples of non-neoplastic white matter tissue. The gene expression levels were significantly higher in glioblastomas than in non-neoplastic white matter in 18 out of 20 genes analyzed: P < 0.00001 for CDKN2C, CKS2, EEF1A1, EMP3, PDPN, BNIP2, CA12, CD34, CDC42EP4, PPIE, SNAI2, GDF15 and MMP23b; and NFIA (P: 0.0001), GPS1 (P: 0.0003), LAMA1 (P: 0.002), STIM1 (P: 0.006), and TASP1 (P: 0.01). Five of these genes are located in contiguous loci at 1p31-36 and 2 at 17q24-25 and 8 of them encode surface membrane proteins. PDPN and CD34 protein expression were evaluated by immunohistochemistry and they showed concordance with the PCR results. The present results indicate the presence of 18 overexpressed genes in human primary glioblastomas that may play a significant role in the pathogenesis of these tumors and that deserve further functional investigation as attractive candidates for new therapeutic targets.

Brain tumors in the first three years of life: a review of twenty cases

OBJECTIVE AND METHOD: To review the clinical and neuropathological findings as well as the type of therapy and outcome in 20 infants under 3 years-old with central nervous system (CNS) tumor. They were treated at the Department of Neurology, "Hospital das Clínicas" University of São Paulo Medical School, from January 1997 to May 2001. RESULTS: Astrocytoma was the most common histological type (n=7), followed by ependymoma (n=3), medulloblastoma (n=2), craniopharyngioma (n=2) and desmoplastic ganglioglioma (n=2). The location of the tumor was predominantly supratentorial. Mean follow-up time was 20.2 months with recurrence in 7 cases. For each type of tumor we have emphasized the treatment currently recommended. CONCLUSION: Although follow-up time is not sufficient for analyzing survival, a trend of improvement in prognosis was noted, compared to another series of cases from our Institution that had been evaluated before 1990.

Intracranial meningiomas: magnetic resonance imaging findings in 78 cases

OBJECTIVE: To present the magnetic resonance (MR) imaging findings of 78 patients with meningiomas diagnosed in a single institution. METHOD: 78 patients with histological proven intracranial meningioma were studied. There were 52 female and 26 male patients (median=56 years). All MR imaging examinations were performed with 1.5-T MR imaging unit with standard protocol. The images were studied by two neuroradiologists, who reached the decisions regarding the findings by consensus. RESULTS: Most of the tumors showed low signal on T1- (60%) and high signl on T2- (68%) and FLAIR (69%) weighted images. Also, the lesions showed heterogeneous signal on T1 (60%), T2 (68%) and FLAIR (64%) sequences. After contrast administration, 83% (n=65) of the tumors presented acentuated and 17% (n=13) showed moderate enhancement. The tumors were located in the frontal lobe in 44% of the cases, in the parietal lobe in 35%, the occipital lobe in 19% and the temporal lobe in 12% of the patients. Areas of vasogenic edema around the tumors were seen in 90% of the cases. Twenty six per cent of the cases showed bone infiltration, and the dural tail sign was seen in 59% of the tumors. CONCLUSION: Intracranial meningiomas usually show heterogeneous low signal on T1- and high signal on T2-weighted and FLAIR images, with intense enhancement after contrast administration. The frontal and parietal lobes are commonly affected. In addition, brain edema, dural tail sign and bone infiltration are the most frequent associated findings.

Ganglioneuroblastoma of the cerebellum: neuroimaging and pathological features of a case

OBJECTIVE: To report a case of ganglioneuroblastoma of cerebellum, with emphasis to the neuroimaging and pathological findings. CASE REPORT: A one year and eight-month-old girl presented with a two-month history of hypoactivity and tremor in the legs. The MRI showed an enhancing cerebellar mass hypointense on T1 and hyperintense on T2-weighted images. The patient underwent a craniotomy with resection of the lesion. The histological and immunohistochemical studies defined the diagnosis of ganglioneuroblastoma. CONCLUSION: The MRI findings of our case showed no features which could help in the differentiation between ganglioneuroblastoma and the other common types of posterior fossa neoplasms in the pediatric population.

Astrocitoma subependimário de células gigantes em pacientes com esclerose tuberosa: achados em ressonância magnética de dez casos

OBJETIVO: Relatar os achados de ressonância magnética (RM) em 10 casos de astrocitoma subependimário de células gigantes (ASCG) em pacientes com esclerose tuberosa (ET). MÉTODO: Foram estudados de forma retrospectiva 10 pacientes com ET e diagnóstico histológico comprovado de ASCG. Quatro pacientes eram do sexo masculino e seis do feminino, com idade média de 15,7 anos. Todos os pacientes foram investigados com RM, sendo os exames revisados por dois radiologistas, havendo decisão por consenso sobre os achados de imagem. Foram analisados os seguintes achados: localização, dimensões, intensidade de sinal em T1/T2, realce pós-contraste e outros achados associados. RESULTADOS: Todos os pacientes apresentaram lesão única sugestiva de ASCG, medindo entre 1,5 cm e 8 cm em seu maior diâmetro. Oito lesões foram encontradas junto ao forame de Monro (80%) e duas adjacentes ao corpo do ventrículo lateral (20%). Os tumores apresentavam nas imagens pesadas em T1 médio sinal (70%) e em T2 alto sinal (100%), com realce intenso após a administração do gadolínio (100%). CONCLUSÃO: Os astrocitomas subependimários de células gigantes em pacientes com ET em geral apresentam-se como lesão única próxima ao forame de Monro, com médio sinal nas imagens ponderadas em T1, alto sinal em T2 e realce intenso após a administração de contraste.

Wilson's disease with myoclonus and white matter lesions

White matter lesions (WML) and epilepsy have been occasionally seen in Wilson's disease. No cases of generalized myoclonus have been reported so far. We present a patient with psychiatric symptoms starting at age 16, followed by tremor, generalized dystonia and severe generalized myoclonus. In addition to classical findings, the MRI showed also extensive WML in temporal, parietal and frontal regions, preserving interhemispheric fibers. Necropsy revealed marked alterations of white matter, cortex and basal ganglia. We subsequently review the literature concerning WML and myoclonus in Wilson's disease.

Optimizing therapy of seizures in patients with HIV and cysticercosis

Worldwide, about 40 million people are living with HIV and 50 million people have neurocysticercosis (NCC). About 5% of patients with HIV and the majority of patients with NCC develop recurrent seizures. Mechanisms of seizure production in HIV include mass lesions, meningitis, encephalitis, and ischemia. Seizures in NCC may occur at all stages of cyst development, from the vesicular and colloidal to the calcified stages. Seizures in HIV present special problems with regard to choice of antiepileptic drug (AED) and the potential for drug-drug interactions with antiretroviral (ARV) treatments. Newer AEDs with simpler pharmacokinetic profiles may be the preferred agents, particularly when protease inhibitors form part of ARV regimens. Seizures in NCC are easily controlled with the older AEDs. Although there has been some debate about the value of antiparasitic drugs in NCC, accumulating data suggest that the use of these agents in active disease decreases the risk for development of chronic epilepsy.

Brain bank of the Brazilian aging brain study group - a milestone reached and more than 1,600 collected brains

INTRODUCTION

Brain banking remains a necessity for the study of aging brain processes and related neurodegenerative diseases. In the present paper, we report the methods applied at and the first results of the Brain Bank of the Brazilian Aging Brain Study Group (BBBABSG) which has two main aims: (1) To collect a large number of brains of elderly comprising non-demented subjects and a large spectrum of pathologies related to aging brain processes, (2) To provide quality material to a multidisciplinar research network unraveling multiple aspects of aging brain processes and related neurodegenerative diseases.

METHODS

The subjects are selected from the Sao Paulo Autopsy Service. Brain parts are frozen and fixated. CSF, carotids, kidney, heart and blood are also collected and DNA is extracted. The neuropathological examinations are carried out based on accepted criteria, using immunohistochemistry. Functional status are assessed through a collateral source based on a clinical protocol. Protocols are approved by the local ethics committee and a written informed consent form is obtained.

RESULTS

During the first 21 months, 1,602 samples were collected and were classified by Clinical Dementia Rating as CDR0: 65.7%; CDR0.5:12.6%, CDR1:8.2%, CDR2:5.4%, and CDR3:8.1%. On average, the cost for the processing each case stood at 400 US dollars. To date, 14 laboratories have been benefited by the BBBABSG.

CONCLUSION

The high percentage of non- demented subjects and the ethnic diversity of this series may be significantly contributive toward aging brain processes and related neurodegenerative diseases understanding since BBBABSG outcomes may provide investigators the answers to some additional questions.

Cortical seeding of a craniopharyngioma after craniotomy: case report

BACKGROUND

Cortical seeding of a craniopharyngioma has been rarely reported. We present a case that ectopically recurred along the tract of a previous surgical route.

METHODS

A 27-year-old woman presented earlier with a suprasellar craniopharyngioma. A left frontotemporal craniotomy was done with subtotal resection of the tumor because it was strongly adhered to the optic chiasm. Histopathology confirmed the diagnosis of craniopharyngioma. Six months after, the patient presented with decreased visual acuity and diplopia. She was reoperated through the previous craniotomy with a total resection. One year after the second surgery, the patient presented with seizures that were difficult to control. Magnetic resonance imaging revealed a contrast-enhancing tumor with cystic and solid components on the left temporal lobe cortex. The primary tumor bed was intact. The patient was reoperated, and the temporal lobe tumor was totally removed. Histologic studies showed an adamantinomatous craniopharyngioma. The patient was free of neurologic abnormalities, and no new lesion was found in the magnetic resonance imaging performed 1 year after the last surgery.

CONCLUSIONS

Although craniopharyngiomas exhibit a benign histopathologic pattern, a total resection combined with careful inspection and irrigation of the surgical field is the optimal treatment for preventing local and ectopic recurrences. It is strongly recommended that the concerned patients have a long-term clinical and neuroimaging follow-up.

Proton MR spectroscopy and imaging of a galactosemic patient before and after dietary treatment

We describe how proton MR spectroscopy ((1)H-MR spectroscopy) was useful in elucidating the diagnosis of galactosemia in an undiagnosed 6-month-old infant. In vivo (1)H-MR spectroscopy of the brain showed a doublet at 3.7 parts per million, which was identified as galactitol (Gal-ol) by in vitro (1)H-MR spectroscopy of the urine. Galactosemia was subsequently confirmed by laboratory tests and treatment was initiated. A follow-up brain MR imaging and (1)H-MR spectroscopy study revealed resolution of white matter lesions and disappearance of Gal-ol peaks.

Asymmetric cortical high signal on diffusion weighted-MRI in a case of Creutzfeldt-Jakob disease

High signal in the cerebral cortex and/or basal ganglia on diffusion-weighted magnetic resonance imaging (DW-MRI) has been described as a good diagnostic marker for sporadic Creutzfeldt-Jakob disease (sCJD). We report a case of sCJD with atypical clinical evolution and unusual DW-MRI findings. A 53-year-old man was seen with a 2-year history of a rapidly progressive dementia and cerebellar ataxia. Cerebrospinal fluid analysis, including the test for 14-3-3 protein, was normal. EEG did not show periodic activity. However, DW-MRI showed gyriform hyperintensity involving practically the entire cortical ribbon of the left hemisphere, whilst being limited to the posterior cingulate gyrus in the right hemisphere. DNA analysis showed no mutations or insertions in the prion protein gene, and homozigozity for methionine in codon 129. A subsequent brain biopsy confirmed the diagnosis of CJD. Thus, high signal on DW-MRI may be limited to the cerebral cortex and may present a very asymmetric distribution in sCJD.

Hidrocefalia derivada na infância: um estudo clínico-epidemiológico de 243 observações consecutivas

Os objetivos deste estudo foram analisar as características epidemiológicas e clínicas de 243 crianças com hidrocefalia derivada, acompanhadas durante 1 a 27 anos, assim como identificar os fatores relacionados aos distúrbios psicomotores, epilepsia e ao óbito. A meningite pós-derivação e os distúrbios mecânicos do sistema foram as complicações mais freqüentes (22,3% e 30,7%, respectivamente). A média de derivação por paciente foi 1,47. Distúrbios motores graves ocorreram em 34,3%, déficit cognitivo em 58,5% e epilepsia em 43,6% dos pacientes. Os distúrbios motores correlacionaram-se positivamente com o grau da hidrocefalia. Houve maior incidência de déficit cognitivo e epilepsia nos casos de hidrocefalia pós-meningite. O óbito ocorreu em 52 pacientes e estes apresentaram um percentual maior de neoplasia do sistema nervoso central e de distúrbios motores na última avaliação, assim como de retirada da primeira derivação por meningite precoce, ocorrida até 2 meses após a derivação.

Galectin-3 as an immunohistochemical tool to distinguish pilocytic astrocytomas from diffuse astrocytomas, and glioblastomas from anaplastic oligodendrogliomas

The distinction of astrocytomas and oligodendrogliomas, mainly pilocytic astrocytomas (PILOs) from infiltrating astrocytomas and oligodendrogliomas (ODs), and high-grade oligodendrogliomas from glioblastomas (GBMs), poses a serious clinical problem. There is no useful immunohistochemical (IHC) marker to differentiate these gliomas, and sometimes the differential diagnosis between them is arbitrary. We identified galectin-3 (Gal-3) as a possible tool to differentiate them based on gene expression profiles of GBMs. We confirmed the differential expression in 45 surgical samples (thirteen GBMs; seven PILOs; 5 grade II ODs; 5 anaplastic oligodendrogliomas [AODs], including 2 Oligo-astrocytomas; 8 diffuse astrocytomas [ASTs], and 7 non-neoplastic samples) by quantification of Gal-3 gene expression by real-time quantitative PCR (rt-PCR). Higher expression of Gal-3 was observed in GBMs and PILOs than in OD, AODs and ASTs. The IHC expression of Gal-3 was evaluated in 90 specimens (fifteen PlLOs, fourteen ASTs, 10 anaplastic astrocytomas, fifteen GBMs, eleven ODs, fifteen AODs, and 10 dysembryoplastic neuroepithelial tumors). The mean labeling score for Gal-3 determined according to the percentage of labeled cells in the tumor bulk was significantly different in GBMs versus AODs and in PILOs versus ASTs. Hence, Gal-3 is differentially expressed in central nervous system tumors, making IHC detection of Gal-3 a useful tool in distinguishing between these gliomas.

Angioleiomyoma of the cavernous sinus: case report

OBJECTIVE AND IMPORTANCE

Angioleiomyomas (ALMs) are relatively rare, benign, vascular soft tissue tumors that occur most frequently in the extremities of middle-aged individuals. To date, only two cases of intracranial ALMs have been described, both with little emphasis on the clinical, surgical, and radiological aspects. Neither of these reported cases of ALM involved the cavernous sinus. Furthermore, there is no previous intracranial ALM magnetic resonance imaging scan described in the literature. This report presents the first case of cavernous sinus ALM, emphasizing the clinical, radiological, and surgical aspects.

CLINICAL PRESENTATION

A 52-year-old man had a 2-year history of horizontal diplopia and frontal headache. Facial numbness and impaired visual acuity in the previous 6 months were also reported. Physical examination revealed paralysis of right Cranial Nerves III, IV, and VI. A decrease in optical acuity was also noted. Computed tomographic and magnetic resonance imaging scans demonstrated a mass lesion located in the right cavernous sinus, which enhanced homogeneously with administration of intravenous contrast medium.

INTERVENTION

A total resection was performed via a right frontotemporal craniotomy and a pretemporal approach with peeling of the middle fossa. The postoperative course was uneventful. Histological examination identified the ALM, with no recurrence noted during follow-up.

CONCLUSION

It is unknown why intracranial ALMs have not been reported more frequently in the literature. Although ALMs are a rare occurrence, misinterpretation of this lesion may also have contributed to the lack of reported cases. Before surgery, ALMs can be distinguished from meningiomas and schwannomas but not from hemangiomas. The prognosis of intracranial ALM is good, as suggested in this case as well as the two previously reported cases.

Angioleiomyoma of the Cavernous Sinus: Case Report

OBJECTIVE AND IMPORTANCE:

Angioleiomyomas (ALMs) are relatively rare, benign, vascular soft tissue tumors that occur most frequently in the extremities of middle-aged individuals. To date, only two cases of intracranial ALMs have been described, both with little emphasis on the clinical, surgical, and radiological aspects. Neither of these reported cases of ALM involved the cavernous sinus. Furthermore, there is no previous intracranial ALM magnetic resonance imaging scan described in the literature. This report presents the first case of cavernous sinus ALM, emphasizing the clinical, radiological, and surgical aspects.

CLINICAL PRESENTATION:

A 52-year-old man had a 2-year history of horizontal diplopia and frontal headache. Facial numbness and impaired visual acuity in the previous 6 months were also reported. Physical examination revealed paralysis of right Cranial Nerves III, IV, and VI. A decrease in optical acuity was also noted. Computed tomographic and magnetic resonance imaging scans demonstrated a mass lesion located in the right cavernous sinus, which enhanced homogeneously with administration of intravenous contrast medium.

INTERVENTION:

A total resection was performed via a right frontotemporal craniotomy and a pretemporal approach with peeling of the middle fossa. The postoperative course was uneventful. Histological examination identified the ALM, with no recurrence noted during follow-up.

CONCLUSION:

It is unknown why intracranial ALMs have not been reported more frequently in the literature. Although ALMs are a rare occurrence, misinterpretation of this lesion may also have contributed to the lack of reported cases. Before surgery, ALMs can be distinguished from meningiomas and schwannomas but not from hemangiomas. The prognosis of intracranial ALM is good, as suggested in this case as well as the two previously reported cases.

Detection of somatic TP53 splice site mutations in diffuse astrocytomas

Alteration in TP53 is the most common genetic event reported for many tumors, including astrocytomas. The majority of studies, on analyzing TP53 mutations, have not included all splice junctions. Consequently, splice site mutations are thought to be relatively infrequent. TP53 were examined for mutations by polymerase chain reaction, single strand conformation polymorphism and direct sequencing in cases of diffuse astrocytomas. We found TP53 mutations in 17.8% (8 out of 45) of the tumors tested: 3 splicing, 3 missense and 2 silent mutations. We have shown that splice site mutations of TP53 are more frequent than previously reported. These findings emphasize the importance of thorough screening of TP53 mutations in gliomas.

Leukoencephalopathy, cerebral calcifications, and cysts

We describe three cases of the rare syndrome of leukoencephalopathy, brain calcifications, and cysts. Conventional MRI, proton spectroscopy, and diffusion-weighted imaging yielded additional information on the disease. Imaging findings favor increased water content rather than a demyelinating process in the pathophysiology of this disease. Clinical features of Coats disease and consanguinity were also encountered.

Frontotemporal dementia with severe thalamic involvement: a clinical and neuropathological study

Frontotemporal dementia (FTD) is the third-leading cause of cortical dementia after Alzheimer's disease and Lewy body dementia, and is characterized by a dementia where behavioral disturbances are prominent and appear early in the course of the disease. We report the case of a 58 year-old man affected by dementia with behavioral disturbances, in addition to rigid-hypokinetic and a lower motor neuron syndrome that were present at later stages of the illness. Neuroimaging studies showed frontotemporal atrophy. Neuropathological studies revealed intense thalamic neuronal loss and astrocytic gliosis, as well as moderate frontotemporal neuronal loss, astrocytosis and spongiform degeneration. Thalamic degeneration has previously been described among the wide group of neuropathological features of FTD. The aim of the present study is to show the clinical and neuropathological aspects of thalamic degeneration in FTD, along with its role in behavioral disturbances, a common finding in this condition.

Leptomeningeal dissemination of pilocytic astrocytoma at diagnosis in childhood: two cases report

Pilocytic astrocytoma (PA) is a benign tumor that rarely spread along the neuraxis. At the moment there are no more than five cases of leptomeningeal dissemination (LD) from PA at diagnosis described in the literature. Different patterns of presentation or recurrence may be noted: local recurrence, malignant transformation, multicentric disease or metastatic disease. LD and multicentric disease can be distinct pathological entities. We report two cases and analyse literature, emphasizing leptomeningeal spread at presentation. Hydrocephalus, biopsy and parcial ressection are likely to be favorable factors to the occurrence of LD. Otherwise, LD may be part of natural history of PA, as evidenced by its ocurrence in non-treated cases.

Evidence of neuronal migration disorders in Knobloch syndrome: clinical and molecular analysis of two novel families

Knobloch syndrome is an autosomal recessive disease characterized by the early onset of severe myopia, vitreoretinal degeneration with retinal detachment, macular abnormalities, and midline encephalocele, mainly in the occipital region. Intra and interfamilial variability is present since the encephalocele is not found in all patients, and the degree of myopia is variable. Analysis of the associated malformations suggests alterations during early neuroectodermal morphogenesis. Only 24 cases have been reported. Recently, the gene responsible for the syndrome, mapped to 21q22.3, was identified. The present study reports on four new cases, revealing the existence of neuronal migratory defects associated with the disorder for the first time.

Molecular analysis of collagen XVIII reveals novel mutations, presence of a third isoform, and possible genetic heterogeneity in Knobloch syndrome

Knobloch syndrome (KS) is a rare disease characterized by severe ocular alterations, including vitreoretinal degeneration associated with retinal detachment and occipital scalp defect. The responsible gene, COL18A1, has been mapped to 21q22.3, and, on the basis of the analysis of one family, we have demonstrated that a mutation affecting only one of the three COL18A1 isoforms causes this phenotype. We report here the results of the screening of both the entire coding region and the exon-intron boundaries of the COL18A1 gene (which includes 43 exons), in eight unrelated patients with KS. Besides 20 polymorphic changes, we identified 6 different pathogenic changes in both alleles of five unrelated patients with KS (three compound heterozygotes and two homozygotes). All are truncating mutations leading to deficiency of one or all collagen XVIII isoforms and endostatin. We have verified that, in exon 41, the deletion c3514-3515delCT, found in three unrelated alleles, is embedded in different haplotypes, suggesting that this mutation has occurred more than once. In addition, our results provide evidence of nonallelic genetic heterogeneity in KS. We also show that the longest human isoform (NC11-728) is expressed in several tissues (including the human eye) and that lack of either the short variant or all of the collagen XVIII isoforms causes similar phenotypes but that those patients who lack all forms present more-severe ocular alterations. Despite the small sample size, we found low endostatin plasma levels in those patients with mutations leading to deficiency of all isoforms; in addition, it seems that absence of all collagen XVIII isoforms causes predisposition to epilepsy.

Craniopharyngioma involving the infrasellar region: a case report and review of the literature

Craniopharyngiomas are most commonly located in the intradural suprasellar region. However, ectopic craniopharyngiomas can originate in the infrasellar region. The authors present the case of an 8-year-old boy diagnosed with a large cystic craniopharyngioma involving the nasal cavities and maxillary, ethmoid and sphenoid sinuses, in addition to the sella turcica. The primary symptoms of this patient were nasal obstruction, unilateral decreased visual acuity and exophthalmos. He subsequently underwent combined radical resection of the tumor by means of an endonasal transsphenoidal approach followed by radiation therapy. During the surgery, the dura mater of the sellar floor was found to be intact. The neuroradiological and surgical findings suggested that this tumor originated in the extradural infrasellar region and invaded the sella turcica.

Friedreich's ataxia: clinical and molecular study of 25 Brazilian cases

INTRODUCTION

Friedreich's ataxia is a neurodegenerative disorder whose clinical diagnostic criteria for typical cases basically include: a) early age of onset (< 20 or 25 years), b) autosomal recessive inheritance, c) progressive ataxia of limbs and gait, and d) absence of lower limb tendon reflexes.

METHODS

We studied the frequency and the size of expanded GAA and their influence on neurologic findings, age at onset, and disease progression in 25 Brazilian patients with clinical diagnosis of Friedreich's ataxia - 19 typical and 6 atypical - using a long-range PCR test.

RESULTS

Abnormalities in cerebellar signs, in electrocardiography, and pes cavus occurred more frequently in typical cases; however, plantar response and speech were more frequently normal in this group when the both typical and atypical cases were compared. Homozygous GAA expansion repeats were detected in 17 cases (68%) - all typical cases. In 8 patients (32%) (6 atypical and 2 typical), no expansion was observed, ruling out the diagnosis of Friedreich's ataxia. In cases with GAA expansions, foot deformity, cardiac abnormalities, and some neurologic findings occurred more frequently; however, abnormalities in cranial nerves and in tomographic findings were detected less frequently than in patients without GAA expansions.

DISCUSSION

Molecular analysis was imperative for the diagnosis of Friedreich's ataxia, not only for typical cases but also for atypical ones. There was no genotype-phenotype correlation. Diagnosis based only on clinical findings is limited; however, it aids in better screening for suspected cases that should be tested. Evaluation for vitamin E deficiency is recommended, especially in cases without GAA expansion.

Inter-laboratory comparison of DNA preservation in archival paraffin-embedded human brain tissue from participating centres on four continents

DNA extracted from formalin-fixed and paraffin-embedded brain tissue is known to contain as yet ill-characterized inhibitors of the PCR process. As part of a project that aims to clarify the role of mitochondrial DNA sequence variation in human neurodegenerative diseases using DNA from various ethnic backgrounds, we have investigated factors that influence the preservation of archival DNA and its suitability for PCR. In this study, neuropathological tissue samples were analysed that had been routinely processed in 18 international centres on four continents. Following DNA extraction, PCR amplification of mitochondrial and nuclear DNA sequences was performed with and without additional purification of the template DNA. In addition, the DNA used for PCR was analysed by HPLC. Phosphate-buffered formalin proved to be a superior fixative compared with unbuffered aldehyde: DNA extraction resulted in greater yields, the molecular weight of the isolated DNA was higher and PCR was more successful. PCR inhibitors were identified as (1) high concentrations of small (<300 bp) DNA fragments that competitively compete with template DNA and (2) contaminants of the DNA template solution including denatured protein that cannot be completely removed by phenolic extraction. HPLC analysis did not reveal significant qualitative differences between DNA isolated from fresh-frozen tissue samples and DNA recovered from formalin-fixed, paraffin-embedded brain tissue. The fact that DNA could be amplified from the majority of tissue specimens in this study suggests that rare diseases and diseases where ethnic background plays an important role can be sampled for genetic polymorphism analysis on a global scale using archival neuropathological collections.